<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>修改 x ，person 的属性也会改变</title>
</head>

<body>
    <p>JavaScript 对象是可变的。</p>
    <p>拷贝的对象改变来，原始的也会跟着改变。</p>
    <p id="demo"></p>
    <script>
        var person = { firstName: "John", lastName: "Doe", age: 50, eyeColor: "blue" }

        var x = person;
        x.age = 10;

        document.getElementById("demo").innerHTML =
            person.firstName + " is " + person.age + " years old.";
    </script>
</body>

</html>